Television scanning device



Filed Feb.

Patented Dec. 18, 1934 UNITED STATES TELEVISION SCANNING DEVICE Charles Francis Jenkins, Washington, D. 0., assignor, by mesne assignments, to Radio Corporation of America, a corporation of Delaware Application February 1, 1930, Serial No. 425,271

2 Claims. (01. 178-6) This invention relates to scanning means in radiomovies and television receivers, and has for its principal object a method and means for using more efficiently than heretofore the small currents employed in radio channels.

This is accomplished by applying all of the radio set energy output to the elementary light area visible at any time. That is, no light is produced beyond the boundary of a single elementary area, which, in a 48-line picture is but 1/2304 (48x48) part of the whole picture area.

An incidental advantage is that the picture is built up in white light, not the pink of the neon lamp. There is no lamp in this new scanning mechanism.

With these and other objects in view, the invention consists in the novel details of construction and combination of parts more fully hereinafter disclosed, illustrated in the accompanying drawing, and particularly pointed out in the claims.

In the schematic drawing herewith, Figure 1 is a section on line x-y of Figure 2, the latter a side elevation. A is a drum, having apertures B located in a four-turn helical path in the shell thereof; D radial wires supported in the hub E, and in the insulating support lining F of the shell; G a terminal of the lead-in wire H. In actual construction there would be four such lead-in wires, one for each helical row of radial wires. To avoid confusion in the drawing, only one lead-in wire, H, is shown. Each lead-in wire would perform in exactly the same way as wire I-I, when each helical row of arc-gaps is being served by such wire, made alive by the distributor switch referred to in the next paragraph. The wire K completes the circuit through the shell; with a jump spark gap at S, between the bent-over end of the wire D and the adjacent edge of the hole in the shell of the drum. Hub A2 is bored out at A3 to fit on a suitable motor to give rotation to the drum. M is a mask lying above the drum, the opening M2 therein forming a boundary for the received picture.

The incoming amplified radio current from the source T is distributed to the lead-in wires of the arc-gaps of the four helices in proper sequence by any suitable distributor, as, for example, an automobile high-tension current distributor, too well known to require description here.

In the operation of this picture receiver, the rotation of the drum carries the inner ends of wires D over the terminal G of lead-in wire H, either in contact with terminal G or within jump spark distance thereof. Consequently the incoming picture current, voltage-amplified, flames across the successive gaps S. The contact of each wire D with terminal G corresponds in angle with the arcuate movement of the flame gap S at the outer end of wires D as each in succession passes under the mask M. As the flame gaps pass in succession, under the opening M2 of mask M, and lighted up in an order controlled by the incoming radio signals, a picture simulating a distant subject or scene is built up on the eye of the observer.

While this new light-source in radiovision and radiomovie receivers is applicable to the disc scanner, the drum principle of scanning (shown in Patents #l,683,137 and 1,730,976), is so superior that the greatest advantage of the new light-source is attained when applied to the drum scanner.

Further, the light-source is not located in the centre of the drum, but at the point of vision, thus conserving the light loss due to dissipation and absorption in whatever medium exists between the hub and the shell of the drum.

Again, the brilliancy of the light-source, as with a lightning flash, is largely a function of the voltage, so a well lighted picture results from a relatively small current.

And as electronic tube amplification is a voltage rather than a current amplification, this flaming-arc gap light source is admirably adapted to present electronic practice.

Obviously the arc-gap flame has a frequency comparable to long wave radio carrier frequency, or at least equal to the usual intermediate frequency employed in some radio sets, for the gap frequency must be well above the elementary picture frequency, which in a 48-line picture would be 48x48xl5, that is, 34,560 oscillations per second in television.

It is also true that the material of the arcgap terminals might be selected to influence the color of light source, as, for example, silver, or zinc, to produce a white flame arc.

What I claim, is-- 1. A television apparatus comprising a rotatable apertured scanning device, a series of conducting rods insulatingly mounted in a common hub and projecting radially therefrom, the outer ends of said rods terminating in said apertures and spaced from the edges of said apertures for producing luminous spark discharges entirely within the apertures, means for rotating said rods and said device as a unit, and a common stationary distributing contact for all of said rods.

2. Television apparatus according to claim 1 in which the television scanning device is of metal and serves as a common electrode cooperating with all said conducting rods.

CHARLES FRANCIS JENKINS. 

